Integrity Evaluation of Cement Ring during Fracturing and Flowback of Horizontal Well in Jimsar Shale Oil

Abstract Horizontal well volume fracturing has become the main technology for effective development of unconventional oil and gas. In the process of fracturing and flowback of horizontal wells, the changes of wellbore temperature and pressure will affect the magnitude and distribution of stress in cement sheath, which may lead to compression or tensile failure of cement sheath, or a microclearance between casing and cement sheath. Therefore, based on the elastic theory of thick-walled cylinder, the elastic model of casing cement sheath and formation combination is established, and the finite difference program FLAC3D (Fast Lagrangian Analysis of Contimua in Three-Dimensional) was used to solve the model. The simulation evaluation of several horizontal wells in Jimusar shale oil shows that the main failure mode of cement sheath in horizontal well section is radial compression or circumferential tensile failure in fracturing period, and the main failure mode is a microclearance failure in flowback period. Taking Jimusar shale oil horizontal well JHW00421 as an example, the critical values of wellbore pressure and mechanical parameters of cement when cement sheath fails during fracturing flowback and their relationship are predicted or evaluated. The findings of this study are helpful to better understand and evaluate how different fracturing or flowback operation parameters affect the integrity of cement sheath and the effectiveness of interlayer sealing in horizontal well sections.

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Shale Reservoir 3D Structural Modeling Using Horizontal Well Data: Main Issues and an Improved Method

Frontiers in Earth Science ◽

10.3389/feart.2021.695502 ◽

2021 ◽

Vol 9 ◽

Author(s):

Zhiguo Shu ◽

Guochang Wang ◽

Yang Luo ◽

Chao Wang ◽

Yalin Chen ◽

...

Keyword(s):

Inclination Angle ◽

Horizontal Well ◽

Horizontal Wells ◽

Structural Modeling ◽

Shale Oil ◽

Improved Method ◽

Vertical Wells ◽

3D Structural Modeling ◽

Shale Reservoirs ◽

Well Data

Shale oil and gas fields usually contain many horizontal wells. The key of 3D structural modeling for shale reservoirs is to effectively utilize all structure-associated data (e.g., formation tops) in these horizontal wells. The inclination angle of horizontal wells is usually large, especially in the lateral section. As a result, formation tops in a horizontal well are located at the distinct lateral positions, while formation tops in a vertical well are usually stacked in the same or similar lateral position. It becomes very challenging to estimate shale layer thickness and structural map of multiple formation surfaces using formation tops in horizontal wells. Meanwhile, the large inclination angle of horizontal wells indicates a complicated spatial relation with shale formation surfaces. The 3D structural modeling using horizontal well data is much more difficult than that using vertical well data. To overcome these new challenges in 3D structural modeling using horizontal well data, we developed a method for 3D structural modeling using horizontal well data. The main process included 1) adding pseudo vertical wells at formation tops to convert the uncoupled formation tops to coupled formation tops as in vertical wells, 2) estimating shale thickness by balancing the shale thickness and dip angle change of a key surface, and 3) detecting horizontal well segments landing in the wrong formations and adding pseudo vertical wells to fix them. We used our improved method to successfully construct two structural models of Longmaxi–Wufeng shale reservoirs at a well pad scale and a shale oil/gas field scale. Our research demonstrated that 3D structural modeling could be improved by maximizing the utilization of horizontal well data, thus optimizing the quality of the structural model of shale reservoirs.

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Simulação de Reservatórios de Óleo Leve com Poço Horizontal Hidraulicamente Fraturado

CALIBRE - Revista Brasiliense de Engenharia e Física Aplicada ◽

10.17648/calibre.v2i2.196 ◽

2017 ◽

Vol 2 (2) ◽

Author(s):

Helio Souto

Keyword(s):

Hydraulic Fracturing ◽

Reservoir Simulation ◽

Horizontal Well ◽

Fractured Reservoirs ◽

Horizontal Wells ◽

Preconditioned Conjugate Gradient ◽

Hydraulic Fractures ◽

Tight Oil ◽

Wellbore Pressure ◽

Fractured Horizontal Wells

Since the 1960s, because of the relevance to the oil industry, the numerical simulation of hydrocarbon reservoirs has received special attention and has been the subject of extensive studies. The main goal of computational modeling and the use of numerical methods for reservoir simulation is to allow better placement and control of wells, so that there is a optimized oil recovery. In this work, production of hydraulically fractured horizontal wells in light tight oil reservoirs will be studied. In this case, fractures do not form a continuous conductive network and can communicate hydraulically with only the horizontal producer well. In order to do that, a simulator for three-dimensional oil flow in reservoirs, suitable for applications in the field scale, already developed, using the Cartesian coordinate system and a finite difference approach, will be applied for the study of hydraulically fractured horizontal wells. Originally, this simulator and its grid refinement tools had been used only on the simulation of naturally fractured reservoirs. The nonlinear partial differential equation resulting from physical-mathematical modeling, written in terms of pressure, will be solved numerically after discretization and linearization using the Preconditioned Conjugate Gradient method. The main objective is to study the combined effects of hydraulic fractures and horizontal well on the wellbore pressure profile, considering different light tight oil production scenarios. Numerical simulations displayed the influence of important parameters on the well-reservoir system in study, such as fracture permeability and matrix porosity. A study of this type is relevant on the discussion of reservoir production strategies, helping on the decisions about a hydraulic fracturing operation in order to obtain economic viability for the hydrocarbons recovery project.Keywords: reservoir simulation, light tight oil, horizontal well, hydraulic fracturing, nite diferences method.

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The Interpretation Technique of Rate Transient Analysis Data in Fractured Horizontal Wells

10.2118/206484-ms ◽

2021 ◽

Author(s):

Ruslan Rubikovich Urazov ◽

Alfred Yadgarovich Davletbaev ◽

Alexey Igorevich Sinitskiy ◽

Ilnur Anifovich Zarafutdinov ◽

Artur Khamitovich Nuriev ◽

...

Keyword(s):

Hydraulic Fracturing ◽

Transient Analysis ◽

Horizontal Well ◽

Horizontal Wells ◽

Data Interpretation ◽

Analysis Data ◽

Well Logging ◽

Rate Transient Analysis ◽

Fractured Horizontal Well ◽

Fractured Horizontal Wells

Abstract This research presents a modified approach to the data interpretation of Rate Transient Analysis (RTA) in hydraulically fractured horizontal well. The results of testing of data interpretation technique taking account of the flow allocation in the borehole according to the well logging and to the injection tests outcomes while carrying out hydraulic fracturing are given. In the course of the interpretation of the field data the parameters of each fracture of hydraulic fracturing were selected with control for results of well logging (WL) by defining the fluid influx in the borehole.

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Improving Proppant Placement Success in Horizontal Wells in Layered Reservoirs in the Sultanate of Oman

10.2118/205919-ms ◽

2021 ◽

Author(s):

Andrew Boucher ◽

Josef Shaoul ◽

Inna Tkachuk ◽

Mohammed Rashdi ◽

Khalfan Bahri ◽

...

Keyword(s):

Horizontal Well ◽

Complex Geometry ◽

Horizontal Wells ◽

Vertical Position ◽

Sultanate Of Oman ◽

Vertical Wells ◽

Multiple Fractures ◽

Initiation Point ◽

Interval Selection ◽

Geological Units

Abstract A gas condensate field in the Sultanate of Oman has been developed since 1999 with vertical wells, with multiple fractures targeting different geological units. There were always issues with premature screenouts, especially when 16/30 or 12/20 proppant were used. The problems placing proppant were mainly in the upper two units, which have the lowest permeability and the most heterogeneous lithology, with alternating sand and shaly layers between the thick competent heterolith layers. Since 2015, a horizontal well pilot has been under way to determine if horizontal wells could be used for infill drilling, focusing on the least depleted units at the top of the reservoir. The horizontal wells have been plagued with problems of high fracturing pressures, low injectivity and premature screenouts. This paper describes a comprehensive analysis performed to understand the reasons for these difficulties and to determine how to improve the perforation interval selection criteria and treatment approach to minimize these problems in future horizontal wells. The method for improving the success rate of propped fracturing was based on analyzing all treatments performed in the first seven horizontal wells, and categorizing their proppant placement behavior into one of three categories (easy, difficult, impossible) based on injectivity, net pressure trend, proppant pumped and screenout occurrence. The stages in all three categories were then compared with relevant parameters, until a relationship was found that could explain both the successful and unsuccessful treatments. Treatments from offset vertical wells performed in the same geological units were re-analyzed, and used to better understand the behavior seen in the horizontal wells. The first observation was that proppant placement challenges and associated fracturing behavior were also seen in vertical wells in the two uppermost units, although to a much lesser extent. A strong correlation was found in the horizontal well fractures between the problems and the location of the perforated interval vertically within this heterogeneous reservoir. In order to place proppant successfully, it was necessary to initiate the fracture in a clean sand layer with sufficient vertical distance (TVT) to the heterolith (barrier) layers above and below the initiation point. The thickness of the heterolith layers was also important. Without sufficient "room" to grow vertically from where it initiates, the fracture appears to generate complex geometry, including horizontal fracture components that result in high fracturing pressures, large tortuosity friction, limited height growth and even poroelastic stress increase. This study has resulted in a better understanding of mechanisms that can make hydraulic fracturing more difficult in a horizontal well than a vertical well in a laminated heterogeneous low permeability reservoir. The guidelines given on how to select perforated intervals based on vertical position in the reservoir, rather than their position along the horizontal well, is a different approach than what is commonly used for horizontal well perforation interval selection.

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A practical method for planning large number of horizontal wells with a reservoir model for a field development plan

Petrovietnam Journal ◽

10.47800/pvj.2021.10-02 ◽

2021 ◽

Vol 10 ◽

pp. 17-32

Author(s):

Guido Fava ◽

Việt Anh Đinh

Keyword(s):

Horizontal Well ◽

Horizontal Wells ◽

Simulation Software ◽

Production Performance ◽

Development Plan ◽

Regular Pattern ◽

Production Forecast ◽

Advanced Technique ◽

Large Reservoir ◽

Field Development

The most advanced technique to evaluate different solutions proposed for a field development plan consists of building a numerical model to simulate the production performance of each alternative. Fields covering hundreds of square kilometres frequently require a large number of wells. There are studies and software concerning optimal planning of vertical wells for the development of a field. However, only few studies cover planning of a large number of horizontal wells seeking full population on a regular pattern. One of the criteria for horizontal well planning is selecting the well positions that have the best reservoir properties and certain standoffs from oil/water contact. The wells are then ranked according to their performances. Other criteria include the geometry and spacing of the wells. Placing hundreds of well individually according to these criteria is highly time consuming and can become impossible under time restraints. A method for planning a large number of horizontal wells in a regular pattern in a simulation model significantly reduces the time required for a reservoir production forecast using simulation software. The proposed method is implemented by a computer script and takes into account not only the aforementioned criteria, but also new well requirements concerning existing wells, development area boundaries, and reservoir geological structure features. Some of the conclusions drawn from a study on this method are (1) the new method saves a significant amount of working hours and avoids human errors, especially when many development scenarios need to be considered; (2) a large reservoir with hundreds of wells may have infinite possible solutions, and this approach has the aim of giving the most significant one; and (3) a horizontal well planning module would be a useful tool for commercial simulation software to ease engineers' tasks.

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Mathematical description of a bounded oil reservoir with a horizontal well

African Journal of Pure and Applied Sciences ◽

10.33886/ajpas.v2i1.190 ◽

2021 ◽

Vol 2 (1) ◽

pp. 67-76

Author(s):

T. N. Nzomo ◽

S. E Adewole ◽

K. O Awuor ◽

D. O. Oyoo

Keyword(s):

Pressure Distribution ◽

Effective Permeability ◽

Horizontal Well ◽

Horizontal Wells ◽

Oil Reservoir ◽

Vertical Wells ◽

Anisotropic Permeability ◽

Time Approximation ◽

Reservoir Geometry ◽

Short Time

Horizontal wells are more productive compared to vertical wells if their performance is optimized. For a completely bounded oil reservoir, immediately the well is put into production, the boundaries of the oil reservoir have no effect on the flow. The pressure distribution thus can be approximated with this into consideration. When the flow reaches either the vertical or the horizontal boundaries of the reservoir, the effect of the boundaries can be factored into the pressure distribution approximation. In this paper we consider the above cases and present a detailed mathematical model that can be used for short time approximation of the pressure distribution for a horizontal well with sealed boundaries. The models are developed using appropriate Green’s and source functions. In all the models developed the effect of the oil reservoir boundaries as well as the oil reservoir parameters determine the flow period experienced. In particular, the effective permeability relative to horizontal anisotropic permeability, the width and length of the reservoir influence the pressure response. The models developed can be used to approximate and analyze the pressure distribution for horizontal wells during a short time of production. The models presented show that the dimensionless pressure distribution is affected by the oil reservoir geometry and the respective directional permeabilities.

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Prediction of water breakthrough time in horizontal Wells in edge water condensate gas reservoirs

E3S Web of Conferences ◽

10.1051/e3sconf/202021302009 ◽

2020 ◽

Vol 213 ◽

pp. 02009

Author(s):

Quan Hua Huang ◽

Xing Yu Lin

Keyword(s):

Horizontal Well ◽

Negative Impact ◽

Horizontal Wells ◽

Breakthrough Time ◽

Gas Reservoirs ◽

Gas Reservoir ◽

Water Breakthrough ◽

Calculation Results ◽

Seepage Model ◽

Reasonable Prediction

Horizontal Wells are often used to develop condensate gas reservoirs. When there is edge water in the gas reservoir, it will have a negative impact on the production of natural gas. Therefore, reasonable prediction of its water breakthrough time is of great significance for the efficient development of condensate gas reservoirs.At present, the prediction model of water breakthrough time in horizontal Wells of condensate gas reservoir is not perfect, and there are mainly problems such as incomplete consideration of retrograde condensate pollution and inaccurate determination of horizontal well seepage model. Based on the ellipsoidal horizontal well seepage model, considering the advance of edge water to the bottom of the well and condensate oil to formation, the advance of edge water is divided into two processes. The time when the first water molecule reaches the bottom of the well when the edge water tongue enters is deduced, that is, the time of edge water breakthrough in condensate gas reservoir.The calculation results show that the relative error of water breakthrough time considering retrograde condensate pollution is less than that without consideration, with a higher accuracy. The example error is less than 2%, which can be effectively applied to the development of edge water gas reservoir.

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Parameters Optimization of Fractures with One for Injection and Two Others for Production of Horizontal Wells Fracturing on Offshore Oilfields

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.962-965.489 ◽

2014 ◽

Vol 962-965 ◽

pp. 489-493

Author(s):

Zhi Qiang Li ◽

Yong Quan Hu ◽

Wen Jiang Xu ◽

Jin Zhou Zhao ◽

Jian Zhong Liu ◽

...

Keyword(s):

Horizontal Well ◽

Oil Production ◽

Horizontal Wells ◽

Simulation Method ◽

Parameters Optimization ◽

Development Mode ◽

Fracture Conductivity ◽

Fracture Length ◽

Fractured Horizontal Well ◽

Production Research

This article presents a new exploitation method based on the same fractured horizontal well with fractures for injection or production on offshore low permeability oilfields for the purpose of adapting to their practical situations and characteristics, which means fractures close to the toe of horizontal well used for injecting water and fractures near the heel of horizontal well used for producing oil. According to proposed development mode of fracturing, relevant physical model is established, Then reservoir numerical simulation method has been applied to study the effect of arrangement pattern of injection and production fractures, fracture conductivity, fracture length on oil production. Research indicates cumulative oil production is much higher by employing the middle fracture for injecting water compared with using the remote one, suggesting that the middle fracture adopted for injecting water, and hydraulic fracture length and conductivity have been optimized. The proposed development pattern of a staged fracturing for horizontal wells with some fractures applied for injecting water and others for production based on the same horizontal well provides new thoughts for offshore oilfields exploitation.

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The Effect of Well Azimuth or Don't Let Your Landman Plan Your Well Path!

10.2118/spe-173331-ms ◽

2015 ◽

Author(s):

Fen Yang ◽

Larry K. Britt ◽

Shari Dunn-Norman

Keyword(s):

Horizontal Well ◽

Oil And Gas ◽

Horizontal Wells ◽

Horizontal Stress ◽

Well Performance ◽

Gas Reservoirs ◽

Principal Stresses ◽

Lateral Direction ◽

Well Completion ◽

Stimulation Of

Abstract Since the late 1980's when Maersk published their work on multiple fracturing of horizontal wells in the Dan Field, the use of transverse multiple fractured horizontal wells has become the completion of choice and become the “industry standard” for unconventional and tight oil and tight gas reservoirs. Today approximately sixty percent of all wells drilled in the United States are drilled horizontally and nearly all of them are multiple fractured. Because a horizontal well adds additional cost and complexity to the drilling, completion, and stimulation of the well we need to fully understand anything that affects the cost and complexity. In other words, we need to understand the affects of the principal stresses, both direction and magnitude, on the drilling completion, and stimulation of these wells. However, little work has been done to address and understand the relationship between the principal stresses and the lateral direction. This paper has as its goal to fundamentally address the question, in what direction should I drill my lateral? Do I drill it in the direction of the maximum horizontal stress (longitudinal) or do I drill it in the direction of the minimum horizontal stress (transverse)? The answer to this question relates directly back to the title of this paper and please "Don't let your land man drive that decision." This paper focuses on the horizontal well's lateral direction (longitudinal or transverse fracture orientation) and how that direction influences productivity, reserves, and economics of horizontal wells. Optimization studies using a single phase fully three dimensional numeric simulator including convergent non-Darcy flow were used to highlight the importance of lateral direction as a function of reservoir permeability. These studies, conducted for both oil and gas, are used to identify the point on the permeability continuum where longitudinal wells outperform transverse wells. The simulations compare and contrast the transverse multiple fractured horizontal well to longitudinal wells based on the number of fractures and stages. Further, the effects of lateral length, fracture half-length, and fracture conductivity were investigated to see how these parameters affected the decision over lateral direction in both oil and gas reservoirs. Additionally, how does completion style affect the lateral direction? That is, how does an open hole completion compare to a cased hole completion and should the type of completion affect the decision on in what direction the lateral should be drilled? These simulation results will be used to discuss the various horizontal well completion and stimulation metrics (rate, recovery, and economics) and how the choice of metrics affects the choice of lateral direction. This paper will also show a series of field case studies to illustrate actual field comparisons in both oil and gas reservoirs of longitudinal versus transverse horizontal wells and tie these field examples and results to the numeric simulation study. This work benefits the petroleum industry by: Establishing well performance and economic based criteria as a function of permeability for drilling longitudinal or transverse horizontal wells,Integrating the reservoir objectives and geomechanic limitations into a horizontal well completion and stimulation strategy,Developing well performance and economic objectives for horizontal well direction (transverse versus longitudinal) and highlighting the incremental benefits of various completion and stimulation strategies.

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Evaluating the Performance of Horizontal Multi-Frac Wells in a Depleted Gas Condensate Reservoir in Sultanate of Oman

10.2118/205328-ms ◽

2022 ◽

Author(s):

Josef R. Shaoul ◽

Jason Park ◽

Andrew Boucher ◽

Inna Tkachuk ◽

Cornelis Veeken ◽

...

Keyword(s):

Horizontal Well ◽

Horizontal Wells ◽

Gas Condensate ◽

Integrated Analysis ◽

Single Fracture ◽

Reservoir Pressure ◽

Well Test ◽

Vertical Wells ◽

Fracture Conductivity ◽

Half Length

Abstract The Saih Rawl gas condensate field has been producing for 20 years from multiple fractured vertical wells covering a very thick gross interval with varying reservoir permeability. After many years of production, the remaining reserves are mainly in the lowest permeability upper units. A pilot program using horizontal multi-frac wells was started in 2015, and five wells were drilled, stimulated and tested over a four-year period. The number of stages per horizontal well ranged from 6 to 14, but in all cases production was much less than expected based on the number of stages and the production from offset vertical wells producing from the same reservoir units with a single fracture. The scope of this paper is to describe the work that was performed to understand the reason for the lower than expected performance of the horizontal wells, how to improve the performance, and the implementation of those ideas in two additional horizontal wells completed in 2020. The study workflow was to perform an integrated analysis of fracturing, production and well test data, in order to history match all available data with a consistent reservoir description (permeability and fracture properties). Fracturing data included diagnostic injections (breakdown, step-rate test and minifrac) and main fracture treatments, where net pressure matching was performed. After closure analysis (ACA) was not possible in most cases due to low reservoir pressure and absence of downhole gauges. Post-fracture well test and production matching was performed using 3D reservoir simulation models including local grid refinement to capture fracture dimensions and conductivity. Based on simulation results, the effective propped fracture half-length seen in the post-frac production was extremely small, on the order of tens of meters, in some of the wells. In other wells, the effective fracture half-length was consistent with the created propped half-length, but the fracture conductivity was extremely small (finite conductivity fracture). The problems with the propped fractures appear to be related to a combination of poor proppant pack cleanup, low proppant concentration and small proppant diameter, compounded by low reservoir pressure which has a negative impact on proppant regained permeability after fracturing with crosslinked gel. Key conclusions from this study are that 1) using the same fracture design in a horizontal well with transverse fractures will not give the same result as in a vertical well in the same reservoir, 2) the effect of depletion on proppant pack cleanup in high temperature tight gas reservoirs appears to be very strong, requiring an adjustment in fracture design and proppant selection to achieve reasonable fracture conductivity, and 3) achieving sufficient effective propped length and height is key to economic production.

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